1. Field of the Invention
This invention pertains generally to pitless well construction, and more particularly to pitless adapter apparatus for providing a sealed connection between a well drop pipe and a delivery pipe through an opening in the well casing.
2. Description of the Prior Art
In pitless well construction, the well drop pipe which supports the pump at the bottom thereof is connected through a coupling or adaptor to a generally horizontally disposed delivery pipe which delivers the well water to its point of use. The delivery pipe is generally rigidly connected and sealed to the well casing, and the drop pipe is coupled by various types of apparatus to the well casing to be in communication with the delivery pipe. Because of the limited working space within the well casing, various pitless coupling apparatus have been developed wherein a first coupling member is inserted into the opening in the well casing and is rigidly mounted thereto, with the delivery pipe being attached to this first coupling member. A second coupling member, which is attached to the well drop pipe to receive water therefrom, is then passed down into the well casing to slip onto the first coupling member until the two coupling members have their interior bores in communication such that water may be passed therethrough. Because the two coupling members in such coupling schemes are not threaded to each other, a possibility of leakage is presented at the joint between the two coupling members. The releaseable fitting between the two coupling members sometimes allows for play in the joint between the members when a pressure moment is applied to the joint. Such moments result from pressure heads within the pressurized well system, which are sometimes increased by the turning on and off of the pump at the end of the drop pipe, with consequent leakage of water under pressure around the joint and eventual accelerated deterioration of the seal at the joints.
Generally, it is desirable that the coupling member to which the drop pipe is attached be readily removable from the well casing to allow servicing of the coupling and of the drop pipe and pump. In addition, the adapter couplings must be capable of supporting the weight of the pump and drop pipe, and of supporting such weight structurally over a period of time while subject to vibrations and pressure moment stresses.